Wool is one of the important byproducts obtained from sheep.
In comparison to hair, it is more elastic, flexible and curly.
It influences the quality of wool because of its shrinking, strengthening and felting conditions.
In the living condition, the outer wool scales are with wool sweat (grease), wool soap or yolk called suint secreted from special glands to keep the fibre in good condition.
The term wool refers to the whole fleeces, which contain mainly three types of fibres.
Fine wool fibres generally have no medulla or hollow core and keep on growing, e.g. Merino fibre has no medulla.
Hairs are continuously growing long fibres with medulla in part of their length.
Kemps are those coarse as well as short fibres, which cease growing at intervals and are shed into the fleece. Such fibres have medulla throughout their length. The outer coat gradually gets eliminated and the inner coat becomes wool, which is seen in Merino, Romney and Lincoln. The kemp is therefore a remnant of the original outer coat.
Vast quantities of wool, called shorn wool, are derived from shearing.
A fleece is a term denoting the whole coat of wool shorn from a sheep at one time.
In the wool trade, fleeces itself are classified as Merino (or fine), crossbred or medium, lusture long wool and carpet.
Much smaller quantities of wool taken off the pelt of the slaughtered animal are coming forward from slaughterhouses, packing plants or tanneries.
This type of wool is called pulled wool, in contradistinction to the shorn.
Wool as it comes off the sheep, whether shorn or pulled, is called raw wool or grease wool. Such wool contains not only grease but impurities of mineral and vegetable origin and suint.
The difference between clean and grease wool is called shrinkage. This depends on the breed of sheep, husbandry nutrition, the type of soil and so on. The buyer estimates the shrinkage and pays for clean wool only.